RESUMEN Como bebida potencial, el té de hojas de café posee cualidades, tanto de café preparado como de té regular, por lo tanto, será una bebida interesante en los próximos años. Una de las principales cualidades es el contenido fenólico de las hojas, a lo cual, se atribuyen beneficios sobre la salud; sin embargo, el contenido fenólico total (TPC), se puede ver afectado negativamente por el calor, durante el proceso de secado. Hojas de café fueron secadas usando un proceso de secado combinado, tiempo corto y alta temperatura (HTST) y secado convectivo, para establecer los parámetros óptimos de secado, tanto para la preservación del TPC como para la reducción del tiempo de secado. Para obtener conclusiones, un diseño de experimentos rotacional central compuesto (CCRD) fue aplicado. Usando como variables independientes la temperatura y el espesor, se generó una superficie de respuesta, empleando el tiempo, como variable dependiente. El rango de temperatura usado fue entre 80 y 110 y de espesor, entre 1 y 3cm. Los resultados indican que el pretratamiento de HTST redujo significativamente el tiempo de secado, sin afectar el TPC, es decir, el análisis del CCRD sobre el efecto del pretratamiento del HTST en el TPC no obtuvo resultados estadísticamente significativos.

SUMMARY As a potential beverage, coffee leaf tea may possess both qualities of brewed coffee and regular tea. Thus, making it an attractive beverage in years to come. One of the main qualities is the leaf’s phenolic content, which is chiefly attributed with health benefits. However, the leaf’s total phenolic content may be adversely affected by heat during the drying process. Coffee leaves were dried using a combined drying process, high-temperature short-time (HTST) and convective drying, to assess the optimal drying parameters for both total phenolic content preservation and drying time reduction. To reach conclusions, a central composite rotational design (CCRD) was employed. With both temperature and thickness as independent variables, a response surface using time as dependent variable was generated. The temperature ranged from 80°C to 110°C and the thickness from 1cm to 3cm. Results indicate that the HTST pretreatment significantly reduced the drying time without affecting the total phenolic content; that is, the CCRD analysis on the effect of the HTST pretreatment on the total phenolic content did not yield statistically significant results.

RESUMEN En Colombia, los pequeños y medianos productores son responsables de la producción de cerca de 45.000 t año-1 de lulo (Solanum quitoense). Sin embargo, técnicas de manejo poscosecha fáciles y adecuadas a menudo no están disponibles para ser implementadas por este sector de productores. Esta investigación tuvo como objetivo estudiar la hoja de plátano (Musa paradisiaca) como empaque primario para minimizar la pérdida de calidad del lulo almacenado a diferentes temperaturas. Se consideraron parámetros de calidad físicos y químicos en el análisis del proceso de maduración. Pérdida de peso, cambio de color en coordenadas CIELAB, acidez total titulable (ATT), módulo de Young y firmeza se midieron para determinar la calidad del fruto. El uso de hoja de plátano como empaque primario permitió que las pérdidas de peso y el cambio de color producto del proceso de maduración disminuyeran. Los cambios de color en la piel del lulo fueron afectados significativamente por la temperatura de almacenamiento. Para evitar cambios en la ATT, el daño mecánico no es recomendable. Cuando los frutos de lulo se empacaron con hoja de plátano, los valores de módulo de Young y firmeza fueron mayores. Los resultados de esta investigación permiten la comparación de la calidad de lulo bajo el empaque propuesto y los resultados de otros autores quienes usaron empaques convencionales como cajas de madera y cartón. La configuración de empaque propuesta (lulos empacados en hoja de plátano en cajas de plástico de 80x60x20 cm) es una alternativa fácil que permite obtener y preservar la calidad de frutos de lulo por un mayor periodo de almacenamiento.

ABSTRACT In Colombia, the small and médium farmers are responsible for the production of nearly 45.000 t yr-1 of lulo (Solanum quitoense). However adequate and easy techniques for postharvest handling are not often available to be implemented by this sector of the producers. This research aimed to study banana (Musa paradisiaca) leaf as primary packaging to minimize the loss of quality of lulo stored at different temperatures. Chemical and physiological quality parameters were considered in the analysis of the maturation process. Loss weight, color changes in CIELAB coordinates, total titratable acidity (TTA), Young's modulus and firmness were measured to represent the fruit quality. Use of banana leaf as primary package show that weight losses and the color changes result of the ripening process were decreased. The color changes of lulo skin were significantly affected by storage temperature. To avoid changes in TTA, mechanical damage is not recommended. When the lulo fruits were packed with banana leaves, the Young's modulus and firmness values was higher. The results of this research allow the comparison of quality of lulo in the packaging proposal and the results of others researchers who use conventionally packaging like wood crates and carton packaging. The proposal packaging configuration (lulos packed with banana leaf in plastic crates of 80x60x20 cm) is an easy alternative to get and preserve the quality of lulo fruits for a longer storage time.

RESUMO A modelagem matemática permite o dimensionamento de secadores, otimização das condições de secagem e avaliação do desempenho do processo. O objetivo deste trabalho foi descrever o comportamento da secagem de bagaço de laranja utilizando-se os modelos de Page e a segunda lei de Fick, avaliar a energia de ativação (equação de Arrhenius), o teor de água, a atividade de água e a massa específica aparente do produto ao final do processo. Realizou-se a secagem de bagaço de laranja com temperatura do ar convectivo entre 36 e 64 ºC e tempo de aplicação da radiação infravermelha na faixa de 23 a 277 s de acordo com planejamento experimental central composto rotacional. Análise de variância e teste F foram aplicados aos resultados. Ao final dos ensaios de secagem foram observados o teor de água entre 0,09 a 0,87 bs e a atividade de água entre 0,25 e 0,87. A massa específica aparente não variou nas condições estudadas. O modelo empírico de Page demonstrou melhor representação dos dados experimentais do que o modelo de Fick para esfera. A energia de ativação obtida nos tempos de infravermelho de 60; 150 e 244 s foi, respectivamente, 18,491; 14,975 e 11,421 kJ mol-1.

ABSTRACT Mathematical modeling enables dimensioning of dryers, optimization of drying conditions and the evaluation of process performance. The aim of this research was to describe the behavior of orange bagasse drying using Page's and Fick's second law models, and to assess activation energy (using Arrhenius equation), moisture content, water activity and bulk density of product at the end of the process. The drying experimental assays were performed in 2011 with convective air temperature between 36 and 64 ºC and infrared radiation application time in the range from 23 to 277 s in accordance with the experimental central composite rotatable design. Analysis of variance and F-test were applied to results. At the end of the drying process, moisture content was about 0.09 to 0.87 db and water activity was between 0.25 and 0.87. Bulk density did not vary under studied conditions. Empirical Page's model demonstrated better representation of experimental data than the Fick's model for spheres. Activation energy values were about 18.491; 14.975 and 11.421 kJ mol-1 for infrared application times of 60; 150 e 244 s, respectively.